Adding LF To Your House of Worship
Subwoofers placement and technique is tricky business for the church sound engineer. On one hand, we want our mixes to be impactful and we want them to move people. On the other hand, subs are a common source of complaints in houses of worship, at least the ones that I’ve worked in.
How do you balance the need for low frequency impact with what I call the “bass complainers?” Well, the first thing you have to ask yourself is, how often are you getting complaints about the low end?
Just recently, I had someone tell me, “This is the second week that I received a complaint about the bass level in Contemporary Worship.” I honestly couldn’t remember the last time I heard a complaint about the low end, so despite feeling bad that someone didn’t have a good experience, I had to pass it off as an isolated incident.
If I think back over the long term, say the last ten years that I’ve been working at this same church, we have had very few complaints relative to the number of people who have come through the doors. Literally tens of thousands of people have attended our services, and we’ve gotten just a handful of serious complaints over the years. So while I want everyone to have an enjoyable time, it is just not possible to please every single person that comes through the doors.
Placement and Positioning
Many of you have heard the age-old saying “two subs in the air equals one on the ground.” There is truth to this, of course, as the half-space loading of placing a subwoofer on the floor can provide additional output of up to 6 dB (less in the real world of course).
If you are debating whether you should fly or ground-stack your subwoofers, there are many factors aside from just level output alone. For one, consider the aesthetics of the system. I know it seems superficial, and I’m an audio guy after all, but I do care about how the system looks in our worship space.
On our most recent install, I was presented with several options by our AV integrator, such as ground-stacking, having all of the subs flown in the center in one column, having them flown next to the main arrays and having them flown behind the main arrays.
Presented with those options, I chose to have the subs flown behind the mains for several reasons. First, I preferred having the subs closely coupled to the mains, which ruled out ground-stacking and flying the subs in a single center column.
From a time alignment perspective, this made it easy to have the subs in phase with the low frequency drivers all the way through the crossover region, and it provides consistent time alignment from the front to the back of the room.
By having the subs closely coupled to the mains, I was also able to cross them over at a higher frequency, allowing the subs to bear the burden of reproducing the lows rather than relying too heavily on the 8-inch LF drivers in the mains.
Finally, I preferred the clean look of having the subs flown behind the mains. The length of the main array and the sub array are virtually identical, making the subs invisible for most congregants.
To Cardioid or Not to Cardioid
Cardioid subwoofers must be one of the most talked about topics in the live sound industry over the past decade. If your subwoofers are putting too much low-end onto your stage, a cardioid sub array might be the answer.
While such arrays can provide amazing benefits when tuned correctly, they don’t come without a price. In our new building install, we didn’t own enough amplifier channels to put our subs in cardioid. Doing so would have required an additional four-channel amplifier to the tune of over $6,000.
In the interest of not spending unnecessary money, I opted not to do a cardioid array, and I’m glad I did. The way our subs are flown is such that they don’t put much energy onto the stage at all. Putting them in cardioid would have decreased our subwoofer output and provided little benefit in our case.
Drive Techniques
There are numerous ways to drive subs from the console or from your loudspeaker processor. The first and most common option is to have the subwoofer feed derived from the stereo bus along with the rest of the P.A. This is the easiest option and most people I know learned to mix on a system setup this way.
Depending on your church’s talent pool, this could be your best option. If you regularly have volunteers mixing, having a separate subwoofer feed from an aux or a group might be more hassle than it is worth.
I run subs off of a mono subgroup to minimize the use of the separate subwoofer feed as a “sub level control.” Our inputs are either going to the subs or they’re not, plain and simple. If you need more low-end on your kick drum, go to your EQ for that, not to your subwoofer’s aux send!
Subs in houses of worship are a tricky beast to tame. Having gone through different iterations with subs on the ground and subs in the air, I would probably choose to have a combination of both if given the option in the future. While I love the flown subs closely coupled to the mains, you can lose some of the feeling when you don’t have any subs sitting directly on the floor hitting the audience directly in the chest.
Vince Lepore is the technical director at St. Luke’s United Methodist Church in Orlando and teaches live production at Full Sail University
